Yes, poor attenuation and the off flavors associated with stressed yeast, weak fermentation and underpitching might be the result of insufficient aeration. Shaking vigorously for a few minutes is sufficient for aerating low gravity beers up to, perhaps, around 1.050-1.060. It may become limiting at higher gravities. I would imagine your technique comes close to aerating as well as shaking, but I'd consider shaking the carboy a bit anyway, just for insurance.

There are other factors, though. With a proper size starter or a fresh pack of rehydrated dry yeast, the demand for oxygen won't be as great. If you are pitching a less than fresh vial or smack pack of yeast, without a starter, then the demand for oxygen will be greater.